Inexperienced soldiers beset by information (5)
I believe the answer is:
green
'inexperienced' is the definition.
('green' can be similar in meaning to 'inexperienced')
'soldiers beset by information' is the wordplay.
'soldiers' becomes 're' (Royal Engineers).
'beset by' means one lot of letters goes inside another ('beset' could historically mean 'cover').
'information' becomes 'gen' (gen is a kind of information**).
're' inserted within 'gen' is 'GREEN'.
(Other definitions for green that I've seen before include "It's for putting on - colour - inexperienced" , "The colour of inexperience" , "Consultative document" , "Ecologically sound" , "The colour of growing grass" .)